excuse me for being stupid, i really dont know what trans is in the 99sts......is it one that is in all models?
tx
rickyd

It would be called a 4t80e.Very heavy-duty 4 speed auto found behind all northstars.3.73 final drive it found behind sts,etc,concours,and dts.Hope it helps

thanks slowroll....now i know.....................
rickyd